JP2634333B2 - Induction motor control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for controlling the primary frequency of an induction motor and a control device for limiting or controlling the torque generated by the induction motor.

[0002]

2. Description of the Related Art Conventionally, as a control device of this kind, FIG.
The configuration shown in FIG. In the figure, 1 is an induction motor, 21 is a transistor inverter circuit for driving the induction motor 1 at a variable frequency, 22 is a frequency command generator, 23 is a function generator, 24 is a primary voltage command generation circuit, and 25 is PWM. Circuit.

Here, the principle of the frequency control of the induction motor by the control device will be described. FIG. 19 is a T-type equivalent circuit per phase of a known induction motor. In the figure, R ₁ is a primary resistance, R ₂ is a secondary resistance, l ₁ is a primary leakage inductance, l ₂ is a secondary leakage inductance, M
Is the primary and secondary mutual inductance, ω ₁ is the primary frequency, ω
_S is the slip frequency, V ₁ is the primary voltage, E ₀ is the gap induced voltage, I ₁ is the primary current, and I ₂ is the secondary current.

First, the gap magnetic flux Φ ₀ is equal to the induced voltage E ₀ and 1
Since it is determined from the next frequency ω ₁ and the time integral of the voltage becomes a magnetic flux, the equation (1) is established.

[0005]

(Equation 1)

[0006] current I _2r for generating a torque acts on the magnetic flux [Phi _0, the effective amount of the secondary current I _2, i.e., when noted that the induced voltage E is _zero and the phase component, I _2r is From FIG. 19, equation (2) is obtained.

[0007]

(Equation 2)

Further, the generated torque T _e of the induction motor (3) since it is proportional to the product of the magnetic flux [Phi ₀ and the current I _2r is established.

[0009]

(Equation 3)

Next, by substituting equations (1) and (2) into equation (3), equation (4) is obtained.

[0011]

(Equation 4)

[0012] (4) from the torque generated T _e and controls the E ₀ / ω ₁ constant changes depending on the slip frequency omega _S. At this time, the maximum torque _Tmax is obtained by differentiating the equation (4) with the slip frequency ω _S and setting its numerator to zero, which is given by the equation (5).

[0013]

(Equation 5)

Therefore, the maximum torque _Tmax is E ₀ / ω ₁
Is constant, it is irrelevant to the change in ω ₁ .

In practice, however, since the induced voltage E ₀ cannot be easily detected, the primary voltage V ₁ is generally used.
Was proportional to omega _1, it controls the value of V ₁ / omega ₁ constant,
A so-called V / F constant control method is used.

[0016] In this case, the primary frequency omega ₁ is lower region, the voltage drop due to the primary resistance R ₁ can not be ignored with respect to the primary voltage V _1, the voltage component corresponding to R ₁ I ₁ in a low frequency range only in advance how the V ₁ is increased it is used.

Next, the operation of the control device shown in FIG. 18 will be described. The function generator 23 receives the primary frequency command ω ₁ ^* output from the frequency command generator 22 based on the functional relationship shown by the solid line in FIG. Outputs the command V ₁ ^* .

Next, the primary voltage command generation circuit 24 calculates the expression (6) from the primary voltage amplitude command V ₁ ^* and the primary frequency command ω ₁ ^*, and calculates next winding primary voltage command V to be applied to _1u ^*, V _1v ^*, respectively outputs V _{1 w} ^*.

[0019]

(Equation 6)

Next, the PWM circuit 25 _generates a transistor (not shown) constituting the transistor inverter circuit 21 in accordance with these primary voltage commands V _1u ^* , V _1v ^* , V _1w ^*.
Is generated, and as a result, the primary voltages V _1u , V _1v and V _1w actually applied to the induction motor ₁ are controlled so as to follow the respective commands. Therefore, it is possible to control the frequency of the induction motor 1, that is, the rotation speed, according to the primary frequency command ω ₁ ^* .

[0021]

The control unit of a conventional induction motor [0005] is constructed as described above, when a large torque at low speed rotation is required, the voltage drop caused by the primary resistance R ₁ As shown in FIG.
It is necessary to set the next voltage command V ₁ ^* higher in advance by the voltage drop.

However, since the value of the primary resistor R ₁ changes depending on the temperature, it is difficult to accurately correct the voltage drop. Therefore, when the voltage correction is smaller than the actual voltage drop, if the load torque is constantly applied to the induction motor, the torque generated during low-speed rotation is insufficient, so that the induction motor cannot be started, and conversely, the voltage correction is not performed. In the case where the amount is large, there is a problem that the operation of the inverter circuit must be stopped in order to protect the inverter circuit from an overcurrent when a large primary current flows during low-speed rotation.

Further, even if the generated torque is the same, different machines driven by the induction motor have different total moments of inertia, so that the rate of change of the rotation speed of the induction motor is different. Therefore, unless the rate of change of the primary frequency command ω ₁ ^* is properly adjusted, acceleration and deceleration of the induction motor cannot be performed normally according to ω ₁ ^* , and a large primary current flows to protect the inverter circuit from overcurrent. However, there is a problem that the operation of the inverter circuit must be stopped.

Further, even when a sudden impact load is applied, since there is no torque limiting function at all, a large primary current flows and the operation of the inverter circuit must be stopped in order to protect the inverter circuit from overcurrent. There was a problem that it did not become.

Further, as described above, the conventional induction motor control device is provided with a predetermined value in accordance with the primary frequency command value.
Since it is configured to output the secondary voltage, there is no function of controlling the torque generated by the induction motor, and torque control was impossible in principle.

[0026] The present invention has been made to solve the problems described above, the value of the primary resistance R ₁ of the induction motor is changed by the temperature, without causing insufficient torque or overcurrent problem It is another object of the present invention to provide a control device for an induction motor that can control the rotational speed of the induction motor to be constantly stable regardless of the rate of change of the primary frequency command ω ₁ ^* driven by the induction motor.

It is another object of the present invention to provide a control device for an induction motor that controls the generated torque of the induction motor so as not to exceed its limit value to prevent overcurrent.

Further , the torque generated by the induction motor is
It is an object of the present invention to obtain a control device for an induction motor that can be controlled to follow the command.

[0029] The control device for the induction motor according to the present invention comprises:
Current detecting means for detecting a primary current of an induction motor; no-load voltage calculating means for generating a no-load voltage command value from a primary frequency command value and an exciting current command value; the primary current and the exciting current command Value and the primary frequency command value
The actual value of the primary magnetic flux generated inside the induction motor is
Magnetic current command value and primary self-inductance of the induction motor
When the primary magnetic flux set value given by the product of
Error current component calculation means for generating an error current component such that the error current component becomes zero, primary resistance correction means for generating a correction amount of a primary resistance set value from the error current component, and correction of the primary resistance set value a correction voltage arithmetic means for generating a correction voltage from the amount and the primary resistance set value and the error current component and the primary current and the previous SL primary frequency command value, the correction voltage and the no-load voltage command value and Primary voltage command calculating means for generating a primary voltage command value for the induction motor from the primary frequency command value ;
It is provided with.

Further, the primary resistance correcting means calculates the error current component.
Calculates (proportional + integral) to generate the correction amount of the primary resistance set value
Is what you do.

Further, the correction voltage arithmetic means primary by multiplying the primary resistance set value and the current component of the measured value of the primary current the sum was converted to d-q axes of the correction amount of the primary resistance set value This is to correct the voltage drop due to the resistance.

Further, a voltage drop due to the correction voltage arithmetic means primary resistance set value and the correction amount and by multiplying <br/> measured value of the primary current to sum the primary resistance of the primary resistance set value It is to be corrected.

Current detecting means for detecting a primary current of the induction motor; and no-load voltage calculating means for generating a no-load voltage command value from a primary frequency command value, a primary frequency correction value and an exciting current command value. And the primary current, the exciting current command value, the primary frequency command value, and the primary frequency correction value.
Actual value of primary magnetic flux generated inside the induction motor by force
Is the excitation current command value and the primary self-input of the induction motor.
Matches the set value of the primary magnetic flux given by the product of the conductance
And error current component calculation means for generating an error current component such that zero when the primary frequency correction primary resistance set value and the error current component the primary current and the previous SL primary frequency command value Correction voltage calculating means for generating a correction voltage from the value, a primary voltage command value of the induction motor from the primary frequency command value, the primary frequency correction value, the no-load voltage command value, and the correction voltage. It is provided with: a primary voltage command calculating means for generating; and a torque limiting means for generating a primary frequency correction value from a predetermined torque current limit value and the primary current.

[0034] The torque limiting means is provided with a predetermined torque voltage.
The difference between the current limit value and the absolute value of the torque current of the primary current is generated.
The difference signal generating means, and the signal from the difference signal generating means.
Change the polarity of the signal according to whether the torque current is positive or negative
First signal switching means for performing the
Has a reset function to process these signals (proportional + integral)
Proportional integration means, and a signal from the proportional integration means
Generates the product of the primary current and the current for the torque and the polarity of the signal
Multiplying means for resetting the proportional integration means according to
According to the polarity of the signal from the multiplying means, the proportional integral
Output from the stage as a primary frequency correction value.
Signal switching means.

Further , the torque limiting means includes a predetermined torque
The difference between the current limit value and the absolute value of the torque current of the primary current is generated.
The difference signal generating means, and the signal from the difference signal generating means.
Change the polarity of the signal according to whether the torque current is positive or negative
First signal switching means for performing the
These signals are integrated and output as a primary frequency correction value
Integrating means having a reset function;
Generating a product of a signal and a torque current of the primary current,
Multiplying means for resetting this integrating means according to the polarity of the signal
And a step.

The torque limiting means is provided with a predetermined torque voltage.
The difference between the current limit value and the absolute value of the torque current of the primary current is generated.
The difference signal generating means, and the signal from the difference signal generating means.
And a first product for generating a product of a signal and a torque current of the primary current.
And the polarity of the signal from the first multiplying means.
Signal switching means for outputting a positive or negative predetermined value according to the
The signal from this signal switching means is integrated and subjected to primary frequency compensation.
Integrating means having a reset function of outputting as a positive value,
The signal from the integrating means and the current corresponding to the torque of the primary current
And the integration means according to the polarity of the signal.
Reset multiplication means.

A current detecting means for detecting a primary current of the induction motor; a no-load voltage calculating means for generating a no-load voltage command value from a primary frequency command value and an exciting current command value;
The primary current, the exciting current command value, and the primary frequency
Primary magnet generated inside the induction motor by inputting
The actual value of the bundle is the exciting current command value and one of the induction motor.
Of primary magnetic flux given by product of secondary self inductance
Correction from the error current component calculation means, the primary resistance set value and the error current component the primary current and the previous SL primary frequency command value for generating an error current component such that zero when matches the value Correction voltage calculation means for generating a voltage, primary voltage command calculation means for generating a primary voltage command value for the induction motor from the primary frequency command value, the no-load voltage command value, and the correction voltage; Torque control means for generating a primary frequency command value from the current command value and the primary current.

Further, the torque control means includes a torque current finger.
The signal of the difference between the command value and the torque current of the primary current is (proportional + product
Minute) and outputs it as the primary frequency command value.
You.

The torque control means includes a torque current finger.
Depending on the polarity of the signal of the difference between the current value and the torque current of the primary current
Signal switching means for outputting a positive or negative predetermined value
Integrates the signal from the signal switching means and sets the primary frequency command value
And integrating means for outputting as

The control device for an induction motor according to the present invention comprises:
Current detecting means for detecting a primary current of an induction motor; no-load voltage calculating means for generating a no-load voltage command value from a primary frequency command value and an exciting current command value; the primary current and the exciting current command Value and the primary frequency command value
The actual value of the primary magnetic flux generated inside the induction motor is
Magnetic current command value and primary self-inductance of the induction motor
When the primary magnetic flux set value given by the product of
Error current component calculation means for generating an error current component such that the error current component becomes zero, primary resistance correction means for generating a correction amount of a primary resistance set value from the error current component, and correction of the primary resistance set value a correction voltage arithmetic means for generating a correction voltage from the amount and the primary resistance set value and the error current component and the primary current and the previous SL primary frequency command value, the correction voltage and the no-load voltage command value and Primary voltage command calculating means for generating a primary voltage command value for the induction motor from the primary frequency command value ;
Therefore, when the primary resistance set value deviates from the true value of the primary resistance of the induction motor, the primary resistance set value is corrected to match the true value of the primary resistance, and the primary magnetic flux is corrected. Is controlled to be constant according to the set value.

Further , the primary resistance correcting means calculates the error current component.
Calculates (proportional + integral) to generate the correction amount of the primary resistance set value
Control the error current component to zero.
become.

Further, the correction voltage arithmetic means primary by multiplying the primary resistance set value and the current component of the measured value of the primary current the sum was converted to d-q axes of the correction amount of the primary resistance set value Since the voltage drop due to the resistance is corrected, when the primary resistance set value deviates from the true value of the primary resistance of the induction motor, the error current component is corrected to be zero.

[0043] Further, a voltage drop due to the correction voltage arithmetic means primary resistance set value and the correction amount and by multiplying <br/> measured value of the primary current to sum the primary resistance of the primary resistance set value Since the correction is performed, when the primary resistance set value deviates from the true value of the primary resistance of the induction motor, the correction is performed so that the error current component becomes zero.

Current detecting means for detecting a primary current of the induction motor; and no-load voltage calculating means for generating a no-load voltage command value from a primary frequency command value, a primary frequency correction value, and an exciting current command value. And the primary current, the exciting current command value, the primary frequency command value, and the primary frequency correction value.
Actual value of primary magnetic flux generated inside the induction motor by force
Is the excitation current command value and the primary self-input of the induction motor.
Matches the set value of the primary magnetic flux given by the product of the conductance
And error current component calculation means for generating an error current component such that zero when the primary frequency correction primary resistance set value and the error current component the primary current and the previous SL primary frequency command value Correction voltage calculating means for generating a correction voltage from the value, a primary voltage command value of the induction motor from the primary frequency command value, the primary frequency correction value, the no-load voltage command value, and the correction voltage. A primary voltage command calculating means for generating the torque; and a torque limiting means for generating a primary frequency correction value from a predetermined torque current limit value and the primary current. And the primary frequency correction value increases or decreases the torque current so that the torque current does not exceed the set value.

Further , the torque limiting means is provided with a predetermined torque current.
The difference between the current limit value and the absolute value of the torque current of the primary current is generated.
The difference signal generating means, and the signal from the difference signal generating means.
Change the polarity of the signal according to whether the torque current is positive or negative
First signal switching means for performing the
Has a reset function to process these signals (proportional + integral)
Proportional integration means, and a signal from the proportional integration means
Generates the product of the primary current and the current for the torque and the polarity of the signal
Multiplying means for resetting the proportional integration means according to
According to the polarity of the signal from the multiplying means, the proportional integral
Output from the stage as a primary frequency correction value.
Signal switching means, the absolute value of the torque current
Is less than a predetermined torque current limit value,
The positive value is set to zero, and the absolute value of the torque
When the current limit value is exceeded, the specified torque current limit value and the primary
The difference between the current torque and the absolute value of the current is processed (proportional + integral).
The processed value is used as the primary frequency correction value.

Further , the torque limiting means is provided with a predetermined torque current.
The difference between the current limit value and the absolute value of the torque current of the primary current is generated.
The difference signal generating means, and the signal from the difference signal generating means.
Change the polarity of the signal according to whether the torque current is positive or negative
First signal switching means for performing the
These signals are integrated and output as a primary frequency correction value
Integrating means having a reset function;
Generating a product of a signal and a torque current of the primary current,
Multiplying means for resetting this integrating means according to the polarity of the signal
And the absolute value of the torque current is equal to the predetermined torque.
When the current is below the current limit value, reset the integrating means.
The primary frequency correction value is set to zero, and the absolute value of the torque
When the torque current is equal to or greater than the specified torque current limit value, the specified torque current
Integrates the difference between the limit value and the absolute value of the torque current of the primary current
The processed value is used as the primary frequency correction value.

Further , the torque limiting means is provided with a predetermined torque current.
The difference between the current limit value and the absolute value of the torque current of the primary current is generated.
The difference signal generating means, and the signal from the difference signal generating means.
And a first product for generating a product of a signal and a torque current of the primary current.
And the polarity of the signal from the first multiplying means.
Signal switching means for outputting a positive or negative predetermined value according to the
The signal from this signal switching means is integrated and subjected to primary frequency compensation.
Integrating means having a reset function of outputting as a positive value,
Torque component current signal and the primary current from the integrating means
And the integration means according to the polarity of the signal.
Reset multiplying means, so that the torque
Integral when the absolute value of
Reset the means to set the primary frequency correction value to zero,
When the absolute value of the divided current is equal to or greater than the specified torque current limit value
Is the primary frequency obtained by integrating the positive or negative predetermined value
It will be a correction value.

A current detecting means for detecting a primary current of the induction motor; a no-load voltage calculating means for generating a no-load voltage command value from a primary frequency command value and an exciting current command value;
The primary current, the exciting current command value, and the primary frequency
Primary magnet generated inside the induction motor by inputting
The actual value of the bundle is the exciting current command value and one of the induction motor.
Of primary magnetic flux given by product of secondary self inductance
Correction from the error current component calculation means, the primary resistance set value and the error current component the primary current and the previous SL primary frequency command value for generating an error current component such that zero when matches the value Correction voltage calculation means for generating a voltage, primary voltage command calculation means for generating a primary voltage command value for the induction motor from the primary frequency command value, the no-load voltage command value, and the correction voltage; Torque control means for generating a primary frequency command value from the current command value and the primary current, so that the primary magnetic flux is controlled to be constant according to the set value,
The primary frequency command value controls the torque generated by the induction motor.

Further, the torque control means includes a torque current finger.
The signal of the difference between the command value and the torque current of the primary current is (proportional + product
Minute) and outputs it as the primary frequency command value.
Generated from the difference between the torque current command value and the torque current of the primary current
The primary frequency command value is used to control the generated torque.
Become.

The torque control means includes a torque current finger.
Depending on the polarity of the signal of the difference between the current value and the torque current of the primary current
Signal switching means for outputting a positive or negative predetermined value
Integrates the signal from the signal switching means and sets the primary frequency command value
And integration means for outputting as
The primary frequency command value generated by integrating the predetermined value of
Will control Luke.

[0051]

[Embodiment 1 ] An embodiment of the present invention will be described below with reference to the drawings. FIG.
FIG. 1 is a block diagram showing the entire control device of an induction motor, wherein 1 is an induction motor, 2 is a current detector, and 3 is a variable frequency power conversion circuit. For example, a transistor inverter circuit 21 and a PWM circuit 25 in a conventional device are used. Consists of 4 is an exciting current command setter, 5 is a no-load voltage calculation circuit, 6 is an error current component calculation circuit, 7 is a correction voltage calculation circuit, 8 is a primary voltage command calculation circuit, 9 is a primary resistance correction circuit, 20 is It is a primary resistance setting device. The configuration of the frequency command generator 22 is exactly the same as that of the conventional device.

FIG. 2 is a block diagram showing a detailed configuration of the above-described no-load voltage calculating circuit 5. In FIG. 2, the no-load voltage calculating circuit 5 includes an input terminal 10 connected to a frequency command generator 22 and , An input terminal 11 connected to the exciting current command setter 4, a coefficient unit 12, a multiplier 13, and an output terminal 14.

FIG. 3 shows the error current component calculation circuit 6 described above.
FIG. 2 is a block diagram showing a detailed configuration of FIG. 1. In the figure, an error current component calculation circuit 6 includes an input terminal 30 connected to an exciting current command setter 4, and input terminals 31 and 32 connected to a current detector 2. An input terminal 33 connected to the frequency command generator 22, coefficient units 34, 35, 36, 47 and 50, adders 37, 45 and 52, a V / F converter 38, a counter 39, ROM 40 and multiplication type D
/ A converters 41 to 44 and subtractors 46, 48 and 5
3, a multiplier 49, a divider 51, and output terminals 54 to 5
6 is comprised.

FIG. 4 is a block diagram showing a detailed configuration of the above-described primary resistance correction circuit 9. In FIG. 4, the primary resistance correction circuit 9 has an input terminal 75 connected to the error current component calculation circuit 6. , An amplifier 76, an amplifying integrator 77,
It comprises an adder 78 and an output terminal 79.

FIG. 5 is a block diagram showing a detailed configuration of the above-described correction voltage calculation circuit 7. In the figure, the correction voltage calculation circuit 7 includes an input terminal 58 connected to the primary resistance setting device 20, An input terminal 59 connected to the primary resistance correction circuit 9, input terminals 60, 61 and 63 connected to the error current component calculation circuit 6, an input terminal 62 connected to the frequency command generator 22, and a multiplier. 64, 69 and 71, amplifiers 65 and 67, adders 57, 66, 70 and 72
, A coefficient unit 68, and output terminals 73 and 74.

FIG. 6 shows the primary voltage command operation circuit 8 described above.
FIG. 3 is a block diagram showing a detailed configuration of FIG.
The next voltage command calculation circuit 8 includes input terminals 80 and 81 connected to the correction voltage calculation circuit 7, an input terminal 82 connected to the no-load voltage calculation circuit 5, and an input terminal connected to the frequency command generator 22. 83 and adders 84, 93 and 96
, V / F converter 85, counter 86, ROM
87, multiplying D / A converters 88 to 91, subtractors 92 and 95, coefficient units 94, 97 to 99, and output terminals 100 to 102.

Next, a control method of the induction motor according to the present invention will be described. As is well known, the primary voltages V _1u , V _1v , V _1w applied to the induction motor ₁ are represented by orthogonal coordinate axes (α
−β coordinate axis) can be converted to the above components V ₁ α and V ₁ β using equation (7).

[0058]

(Equation 7)

On the other hand, V ₁ α and V ₁ β are given by the following equations (7).
It can be converted to V _1u , V _1v , V _1w using the equation (8).

[0060]

(Equation 8)

A similar relationship holds between the primary currents I _1u , I _1v , I _1w and the α-axis components I ₁ α, β-axis components I ₁ β, and (9), (10) It is shown by the formula.

[0062]

(Equation 9)

[0063]

(Equation 10)

Next, the voltage-current equation of the induction motor on the α-β coordinate axis is known and is expressed by equation (11).

[0065]

[Equation 11]

Next, as shown in (12) to (14) to convert the relation on (11) (a d-q coordinate axes) rotation axis for rotating at a primary frequency omega ₁ The coordinate rotation formula is used.

[0067]

(Equation 12)

[0068]

(Equation 13)

[0069]

[Equation 14]

However, the coordinate rotation angle θ ₁ is given by equation (15).

[0071]

(Equation 15)

By substituting equations (12) to (14) into equation (11), V ₁ α, V ₁ β, I ₁ α, I ₁ β, I ₂ α,
Eliminating I ₂ β gives equation (16).

[0073]

(Equation 16)

However, the slip frequency ω _s is given by equation (17).

[0075]

[Equation 17]

Next, the d and q axis components Φ _1d , Φ of the primary magnetic flux Φ _1
1q is publicly known and is represented by equation (18).

[0077]

(Equation 18)

By substituting equation (18) into equation (16), I _2d ,
Eliminating I _2q yields equations (19) and (20).

[0079]

[Equation 19]

[0080]

(Equation 20)

Here, the leakage coefficient σ is given by equation (21).

[0082]

(Equation 21)

Here, it is assumed that the primary magnetic flux Φ ₁ is controlled to be constant according to the set value, and the equation (22) is assumed.

[0084]

(Equation 22)

Here, I _1d ^* is an exciting current command value. Further, considering a steady state, assuming that the differential operator P = 0, (2
By substituting equation (2) into equation (19), equation (23) is obtained. By substituting equation (22) into equation (20), (2
4) Equation is obtained.

[0086]

(Equation 23)

[0087]

(Equation 24)

Therefore, if V _1d and V _1q are given by the equation (23), the equation (22) is established in the steady state, and the primary magnetic flux Φ ₁ is controlled to be constant according to the set value.

Here, in order to improve the damping characteristic of the control system and to improve the stability, it is used that the equation (22) is satisfied, and that I _1d and its command value I _1d ^* _{satisfy the} equation (24). Then, a term for controlling the right side of equation (24) to be zero is added. Thereby, equation (25) is obtained.

[0090]

(Equation 25)

[0091] (25) the set value of primary resistance R ₁ in the formula R ₁
^* Is included. R ₁ is for changing the temperature can not be always set to the true value. Where (1)
By solving the equations (6) and (25) simultaneously, R
₁ ^* <value of I _err becomes positive in the case of R _1, R ₁ in the opposite ^*
It is known that the value of I _err becomes negative when > R _1.
You. Thus, by executing the control according to the control rule of equation (25), even if R ₁ ^* has an error with respect to its true value, deterioration of the control characteristics due to the setting error of R ₁ ^* is suppressed.
Direction will be controlled . However, at a low frequency, the control characteristic is greatly degraded due to a setting error of R ₁ ^* as compared to a high frequency, and the proportional compensation term alone results in poor characteristic.
Can not suppress the reduction, deterioration of the control characteristics is an important problem.

According to the present invention, if R ₁ ^* has an error with respect to its true value, the current error I _err shown by the above equation (25) is not zero, and I _err is set to a predetermined gain. (Proportional + integral), and this is calculated as the correction amount ΔR ₁ ^} of the primary resistance set value R ₁ ^* .

That is, according to the equation (26), the primary resistance set value R
The correction amount ΔR ₁の of ₁ ^* is calculated, and then R ₁ ^* is added as shown in equation (27) to obtain an estimated primary resistance value R ₁ ＾. Then, (25) a R ₁ ^* of (27) obtained by replacing the R ₁ ^ (28) equation is established by the formula.

[0094]

(Equation 26)

[0095]

[Equation 27]

[0096]

[Equation 28]

The above is the control method according to the present invention. Even if the primary resistance changes with temperature, the correction is automatically performed, so that the primary magnetic flux Φ ₁ is always controlled to be constant according to the set value. Control of the induction motor becomes possible.

Next, the operation will be described with reference to FIGS. First, as shown in FIG.
_Iq0 ^* is output by the multiplier 13. That is, the exciting current command I _Id ^* output from the exciting current command setting device 4 via the input terminal 11 is input to the coefficient unit 12 and then output from the frequency command generator 22 via the input terminal 10. When the primary frequency command ω ₁ ^* is multiplied by the multiplier 13, a no-load voltage command V _Iq0 ^* (= L ₁ ω ₁ ^* I _1d ^* ) corresponding to the second term on the right side of V _Iq in equation (28) is obtained. And output from the output terminal 14.

Next, as shown in FIG.
_err , d-axis and q-axis components I _1d and I _{1q of the} primary current are output from the error current component calculation circuit 6. That is, when the primary currents I _1u and I _1v of the induction motor 1 detected by the current detector 2 are input to the input terminals 31 and 32, respectively, the calculation of the equation (9) is performed by the coefficient units 34 to 36 and the adder 37. Then, the α-axis and β-axis components I ₁ α and I ₁ β of the primary current are output from the coefficient unit 34 and the adder 37, respectively.

On the other hand, when the primary frequency command ω ₁ ^* of the analog quantity output from the frequency command generator 22 is input to the V / F converter 38 via the input terminal 33, the frequency becomes the primary frequency command ω ₁ ^*. Is obtained, a counter 39 obtains a digital quantity angle command θ ₁ ^* which is a time integration value of the primary frequency command ω ₁ ^* , and stores values of sin θ ₁ ^* and cos θ ₁ ^*. ROM
The address is input as 40 addresses. As a result, ROM4
From 0, digital quantities of sin θ ₁ ^* and cos θ ₁ ^* are output. Then, the α-axis component I _1α and the β-axis component I _{1β of the} primary current output from the coefficient unit 34 and the adder 37 are output.
And sin θ ₁ ^* and cos output from the ROM 40
The digital amount of θ ₁ ^* is multiplied by a D / A converter 41 to 41
After being input to 44 and multiplied and converted to analog, the adder 45
And input to the subtractor 46, the operation of the expression (29), which is the inverse operation expression of the expression (13), is performed, and the d-axis and q of the primary current are calculated.
The axial components I _1d and I _1q are obtained.

[0101]

(Equation 29)

Thereafter, from these I _1d and I _1q and the exciting current command I _1d ^* output from the exciting current command setting device 4 via the input terminal 30, coefficient units 47 and 50, a multiplier 49 , A divider 51, an adder 52, and a subtractor 53 perform an operation to obtain I _err in the equation (25), and obtain an error current component I obtained as an output of the subtractor 53.
_err is output from the output terminal 54. The adder 45
And I _1d and I _1q obtained as the output of the subtractor 46 are
The signals are output from output terminals 55 and 56, respectively.

Next, as shown in FIG. 4, the correction amount ΔR ₁ ^} of the primary resistance set value R ₁ ^* is output from the primary resistance correction circuit 9. That is, the error current component I _err is output from the error current component calculation circuit 6 via the input terminal 75. As a result, the operation of the equation (26) is performed by the amplifier 76, the amplification type integrator 77 and the adder 78, and the primary resistance set value R
It is output from the ₁ ^* of the correction amount ΔR ₁ ^ as the output terminal 79.

Next, as shown in FIG. 5, the d-axis and q-axis correction voltage components ΔV _1d and ΔV _1q are calculated by the correction voltage component calculation circuit 7.
Output from That is, the primary resistance setting device 20 is the primary resistance set value R ₁ ^* via output the input terminal 58 from, also the primary resistance correcting circuit 1 via the input terminal 59 from 9 primary resistance set value R ₁ ^* Correction amount ΔR ₁ ^} is output. As a result, the calculation of equation (27) is performed, and the primary resistance estimated value R
₁ } is output from the adder 57. The d-axis component I _1d of the primary current, the error current component I _err, and the q-axis component I _{1q of the} primary current are output from the error current component calculation circuit 6 via the input terminals 60, 61 and 63, respectively. .

As a result, the multiplier 64, the amplifier 65, and the adder 66 perform the operation on the right side of V _{1d in} the equation (28), and output from the output terminal 73 as the d-axis correction voltage component ΔV _1d . On the other hand, the error current component I _err and the 1 output from the frequency command generator 22 via the input terminal 62 are output.
From the next frequency command ω ₁ ^* , an amplifier 67, a coefficient unit 68,
By the multiplier 69 and the adder 70, V _{1q of the} equation (28) is obtained.
Is performed, and the multiplier 71 performs the calculation of the first term on the right side of V _{1q in} the equation (28).
Further, when the outputs of the adder 70 and the multiplier 71 are added by the adder 72, the voltage of the second term on the right side of V _1q in equation (28)
That is, the voltage components excluding the no-load voltage are output from the output terminal 74 as the q-axis correction voltage component ΔV _1q .

Next, as shown in FIG.
_1u ^* , V _1v ^* and V _1w ^* are output from the primary voltage command calculation circuit 8. That is, d-axis and q-axis correction voltage components ΔV _1d and ΔV _1q are output from the correction voltage component calculation circuit 7 via the input terminals 80 and 81, respectively. Where (28)
In the equation , since the d-axis component V _1d of the primary voltage is zero when there is no load, ΔV _1d is equal to the d-axis component command V _1d ^{* of the} primary voltage.
Become equal. On the other hand, the adder 84 adds the no-load voltage command V _1q0 ^* output from the no-load voltage calculation circuit 5 via the input terminal 82 to the q-axis correction voltage component ΔV _1q, and the equation (28) Is performed on the right side of V _1q of
It is output as the q-axis component command V _1q ^* of the next voltage.

After that, when a primary frequency command ω ₁ ^* is input from the frequency command generator 22 via the input terminal 83,
By the same operation as the correction current component calculation circuit 6 described above, R
Output from OM87 the sin [theta ₁ ^* and cos [theta] ₁ ^*
Is input to the multiplication type D / A converters 88 to 91, multiplied and analog-converted, and then input to the subtractor 92 and the adder 93.
Α-axis component command V ₁ α ^* and β-axis component command V ₁ β of next voltage
^* Is required. Then, coefficient units 94, 97 to 99,
The operation of equation (8) is performed by the subtracter 95 and the adder 96, and the primary voltage commands _V1u ^* , _V1v ^*, and _V1w ^* are output from the output terminals 100 to 102, respectively.

Thereafter, these primary voltage commands V _1u ^* , V
_{When 1v} ^* and V _1w ^* are input to the variable frequency power conversion circuit 3, the actual value of the primary voltage applied to the induction motor 1 follows these primary voltage commands by the same operation as the conventional device. Is controlled as follows.

In the above embodiment, the voltage drop due to the primary resistor R ₁ is calculated by calculating the d-axis and q-axis components I _1d , I ₁
Primary resistance set value R ₁ ^* and its correction amount ΔR _{1 に 対 し て} for _1q
Has been shown in the correction voltage calculation circuit using the value obtained by multiplying the primary resistance estimated value R ₁し た by adding the correction voltage calculation circuit. However, the configurations of the correction voltage calculation circuit 7 and the primary voltage command calculation circuit 8 are 7 and 8, the voltage drop may be corrected using the primary currents I _1u and I _1v detected by the current detector 2.

That is, in the correction voltage calculation circuit 7a of the block diagram shown in FIG. 7, the error current component I _{err of the} equation (28) is obtained.
_{Are calculated} and output as correction voltage components ΔV _1d0 and ΔV _1q0 on the d-axis and the q-axis. That is, ΔV _1d0 and ΔV _1q0 are given by Expression (30).

[0111]

[Equation 30]

Further, these correction voltage components ΔV _1d0 , Δ
If via the input terminals 80a and 81a of the V _1Q0 entering the primary voltage calculation circuit 8a of the block diagram shown in FIG. 8, and ignoring the voltage drop caused by each primary resistance R ₁ from the coefficient multiplier 97 to 99 Primary voltage commands V _1u0 ^* , V _1v0 ^*, and V _1w0 ^* are output.

Next, from the primary resistance setting device 20 to the input terminal 1
13, the primary resistance set value R ₁ ^* is output, and the primary resistance correction circuit 9 outputs the correction amount ΔR ₁の of the primary resistance set value R ₁ ^* via the input terminal 114. You.
Then, the primary resistance estimated value R ₁出力 is output from the adder 115, and is multiplied by the multiplier 107 by the U-phase primary current output from the current detector 2 via the input terminal 103. Since the voltage drop V _Ru by the primary resistor R ₁ is obtained,
Output terminal 1 when added to V _1u0 ^* by adder 110
1 of U-phase by 00 from the primary resistor R ₁ comprises a voltage drop
The next voltage command V _1u ^* is output.

Similarly, the V-phase primary current output from the current detector 2 via the input terminal 104 and the adder 11
5 is multiplied by the multiplier 108 to obtain a voltage drop V _Vu due to the V-phase primary resistor R _1.
When V _1v0 ^* is added by 1, the output terminal 101 outputs 1
A V-phase primary voltage command V _1v ^* including a voltage drop by the secondary resistor R ₁ is output.

Next, regarding the W phase, first, the known (3)
Using the equation 1), the adder 105 and the sign inverter 106 determine the W-phase primary current I _1w from the primary currents I _1u and I _1v . Similarly, the W-phase primary current, which is the output of the sign inverter 106, and the output of the adder 115 are multiplied by the multiplier 109, and the voltage drop V _Wu due to the W-phase primary resistor R ₁ is obtained. Since it is obtained, V _1W0 ^*
Is added, a W-phase primary voltage command V _1W ^* including a voltage drop due to the primary resistor R ₁ is output from the output terminal 102.

[0116]

(Equation 31)

In the above embodiment, the primary resistance correction circuit 9 is constituted by the amplifier and the amplification type integrator, but may be constituted only by the amplification type integrator. In another embodiment, the voltage drop due to the primary resistance may be corrected in the primary voltage command calculation circuit using the α-axis and β-axis components I ₁ α and I ₁ β of the primary current. . Furthermore, the primary current I _1W
Is calculated from I _1u and I _1v, but a value detected by a current detector can also be used.

Embodiment 2 FIG . Hereinafter, an embodiment of the second invention will be described with reference to the drawings. FIG. 9 is a block diagram showing the entire control device of the induction motor. As in the first embodiment, reference numeral 2 denotes a current detector, and 3 denotes a variable frequency power conversion circuit. And a PWM circuit 25. 4 is an exciting current command setting device, 5 is a no-load voltage calculation circuit, 6 is an error current component calculation circuit, 7 is a correction voltage calculation circuit, 8 is a primary voltage command calculation circuit, 190 is a torque current limit value setting device, 15 Is a torque limiting circuit, and 16 is an adder. The configuration of the frequency command generator 22 is exactly the same as that of the conventional device.

The input terminal 10 of the no-load voltage calculation circuit 5 (see FIG. 2) according to the second invention is connected to an adder 16, and the error current component calculation circuit 6 (see FIG. 3).
Input terminal 33) is also connected to the adder 16. Other configurations of the no-load voltage calculation circuit 5 and the error current component calculation circuit 6 are the same as those of the first invention.

FIG. 10 is a block diagram showing a detailed configuration of the torque limiting circuit 15. In FIG. 10, the torque limiting circuit 15 includes an input terminal 120 connected to a torque current limit value setting device 190, An input terminal 121 connected to the component operation circuit 6, a subtractor 122, a sign inverter 123, signal switches 124 and 129, and a coefficient unit 125
, Amplifying integrator 126 with reset, and adder 127
, Multiplier 128, output terminal 130, absolute value circuit 1
31.

FIG. 11 is a block diagram showing a detailed configuration of the correction voltage calculation circuit 7. In FIG. 11, the correction voltage calculation circuit 7 includes input terminals 60, 61, 63, an input terminal 62 connected to the adder 16, coefficient units 164, 68 and 171, amplifiers 65 and 67, adders 66, 70 and 72, a multiplier 69, and output terminals 73 and 74. It is composed of

The input terminal 83 of the primary voltage command calculation circuit 8 (see FIG. 6) according to the second invention is connected to the adder 16. Other configurations are the same as those of the first invention.

The control method of the induction motor in the second invention is the same as the control method described in the first invention up to the expression (24).

Here, in order to improve the damping characteristic of the control system and to improve the stability, it is used that the expression (22) is satisfied and I _1d and its command value I _1d ^* _{satisfy the} expression (24). Then, a term for controlling the right side of equation (24) to be zero is added. Thereby, equation (32) is obtained.

[0125]

(Equation 32)

[0126] Incidentally, the generated torque T _e of the induction motor, as is known, is determined by equation (33).

[0127]

[Equation 33]

Here, since the expression (22) is established by controlling the induction motor by the expression (32), the expression (34) is obtained by substituting the expression (22) into the expression (33).

[0129]

(Equation 34)

[0130] When the control by the induction motor (32), the generated torque T _e is proportional to the torque current I _1q from equation (34). By transforming equation (34), equation (35) is obtained.

[0131]

(Equation 35)

[0132] than (35), is required torque current I _1q required to generate a constant torque T _e there is an induction motor. Therefore, the generated torque T _e of the induction motor, in order to control so as to follow the command value T _e ^* is
The control of Expression (32) is executed to _satisfy Expression (22), and the torque component current I _1q is further controlled to the value obtained by Expression (35).

Next, the control of the equation (32) is executed, and (2)
When the expression (2) is satisfied, the slip frequency ω _s of the induction motor is given by the expression (36) in a steady state by substituting the expression (22) into the expression (16).

[0134]

[Equation 36]

Furthermore, the primary frequency ω ₁ and the slip frequency ω _s
Is in the relationship of equation (17), so that the slip frequency ω _s is increased, that is, 1 to increase the torque current I _1q.
It is sufficient to increase the following frequencies omega _1, conversely, to reduce the torque current I _1q may reduce the slip frequency omega _s,
That is, the primary frequency ω ₁ may be reduced.

The above is the control method according to the second aspect of the present invention, in which the primary magnetic flux Φ ₁ is constantly controlled as set, and good control of the induction motor becomes possible. In addition, by limiting the torque generated by the induction motor, overcurrent can be suppressed. Further, it is possible to control the generated torque of the induction motor so as to follow the command value.

Next, the operation of the second invention will be described with reference to FIGS.
This will be described with reference to FIG. 11, FIG. 2, FIG. 3, and FIG. FIG.
The primary frequency correction value Δω ₁ ^* output from the torque limiting circuit 15 is added to the primary frequency command value ω ₁ ^* output from the frequency command generator 22 by the adder 16 as shown in FIG. It becomes the frequency command value ω ₁ ^** . Further, the torque current limit value setter 190 outputs the torque current limit value I _1qmax ^* obtained by the equation (35).

Next, as shown in FIG. 2, the no-load voltage command V _Iq0 ^* is output by the multiplier 13. That is, after the exciting current command I _Id ^* output from the exciting current command setting device 4 via the input terminal 11 is input to the coefficient unit 12, the correction 1 output from the adder 16 via the input terminal 10 is output. Multiplying the next frequency command ω ₁ ^** by the multiplier 13
A no-load voltage command V _Iq0 ^* (= L ₁ ω ₁ ^** I _1d ^* ) corresponding to the second term on the right side of V _Iq in equation (32) is obtained and output from the output terminal 14.

Next, as shown in FIG.
_err , d-axis and q-axis components I _1d and I _{1q of the} primary current are output from the error current component calculation circuit 6. That is, when the primary currents I _1u and I _1v of the induction motor 1 detected by the current detector 2 are input to the input terminals 31 and 32, respectively, the calculation of the equation (9) is performed by the coefficient units 34 to 36 and the adder 37. Then, the α-axis and β-axis components I ₁ α and I ₁ β of the primary current are output from the coefficient unit 34 and the adder 37, respectively.

[0140] On the other hand, when the input to the V / F converter 38 via the adder 16 of the analog amount output from the correction primary frequency command omega ₁ ^{* *} input terminal 33, the frequency is corrected primary frequency command omega ₁ A signal of a pulse train proportional to ^** is obtained, and the counter 39 corrects the primary frequency command ω ₁ ^**
The angle command θ ₁ ^* of the digital quantity, which is the time integration value of, is obtained, and the values of sin θ ₁ ^* and cos θ ₁ ^* are input as the address of the ROM 40 in which the values are stored. as a result,
The ROM 40 outputs digital amounts of sin θ ₁ ^* and cos θ ₁ ^* . Thereafter, the coefficient unit 34 and the adder 3
Α component I _1α and β axis of the primary current output from
The component I _1β and the sin θ ₁ ^* output from the ROM 40
And the digital quantities of cos θ ₁ ^* are input to the multiplication type D / A converters 41 to 44, multiplied and analog-converted,
When input to the adder 45 and the subtractor 46, the operation of the expression (29), which is the inverse operation expression of the expression (13), is performed, and the d-axis and q-axis components I _1d and I _{1q of the} primary current are obtained.

Thereafter, from these I _1d and I _1q and the exciting current command I _1d ^* outputted from the exciting current command setting device 4 via the input terminal 30, coefficient units 47 and 50, a multiplier 49 , A divider 51, an adder 52, and a subtractor 53 perform an operation to obtain I _err in the equation (32), and obtain an error current component I obtained as an output of the subtractor 53.
_err is output from the output terminal 54. The adder 45
And I _1d and I _1q obtained as the output of the subtractor 46 are
The signals are output from output terminals 55 and 56, respectively.

Next, the primary frequency correction value Δω ₁ ^* is output from the torque limiting circuit 15 as shown in FIG. That is, the input terminal 120
, A torque current limit value I _1qmax ^* is output, and the error current component calculation circuit 6 outputs a q-axis component of the primary current, that is, a torque component current I _1q via the input terminal 121. . As a result, the torque current I _1q is _calculated by the absolute value circuit 1
The subtractor 122 subtracts the absolute value from the torque current limit value I _1qmax ^* .

Next, the signal switch 124 is provided with a subtractor 122
, An output obtained by inverting the sign of the output of the subtractor 122 by the sign inverter 123, and the torque current I _1q .
When the torque component current I _1q is positive or zero, the output of the subtractor 122 is output, and when the torque component current I _1q is negative, the output of the subtractor 122 is output with its sign inverted by the sign inverter 123. Thereafter, the output of the signal switch 124 is output to the coefficient unit 12
5 and input to the amplification type integrator 126 with reset. The amplifying integrator 126 with reset is integrated by multiplying the output of the signal switch 124 by K _I , and the output is added by the adder 127 to the output of the coefficient unit 125.

Further, the multiplier 128 multiplies the output of the adder 127 by the torque component current I _1q, and outputs the multiplied value to the amplifying integrator 126 with reset and the signal switch 129. As a result, in the amplification type integrator 126 with reset, when the output of the multiplier 128 is positive or zero, the integral amount held inside the integrator is reset to zero. Further, the signal switch 129 outputs the output of the adder 127, zero and the multiplier 128.
When the output of the multiplier 128 is positive or zero, the absolute value of the torque component current I _1q is
Since the value I _1qmax ^* is _exceeded, the output of the adder 127 is
Output from output terminal 130 as primary frequency correction value Δω ₁ ^*
If the output of the multiplier 128 is negative, the torque
The absolute value of I _1q exceeds the torque current limit value I _1qmax ^*
Therefore, zero is output from the output terminal 130.

Next, as shown in FIG. 11, the correction voltage components ΔV _1d and ΔV _1q on the d-axis and the q-axis are output from the correction voltage component calculation circuit 7. That is, the primary current d from the error current component calculation circuit 6 via the input terminals 60, 61 and 63, respectively.
The axis component I _1d , the error current component I _err, and the q-axis component I _{1q of the} primary current are output. As a result, the coefficient unit 164 and the amplifiers 65 and 66 perform the calculation on the right side of V _{1d in} the equation (32), and output the correction voltage component ΔV _1d of the d-axis from the output terminal 73.

On the other hand, the error current component I _err and the adder 16
From the corrected primary frequency command value ω ₁ ^** output from the input terminal 62 via the input terminal 62, the amplifier 67, the coefficient unit 68, the multiplier 69, and the adder 70 determine the right side of V _{1q in} the equation (32). The calculation of the third term is performed, and the calculation of the first term on the right side of V _1q in equation (32) is performed by the coefficient unit 171 .
Further, the outputs of the adder 70 and the coefficient unit 171 are added to the adder 72.
In the equation (32), the voltage of the second term on the right side of V _1q , that is, the voltage component excluding the no-load voltage command V _1q0 ^* is q
It is output from the output terminal 74 as a correction voltage component ΔV _1q for the axis.

Next, as shown in FIG.
_1u ^* , V _1v ^* and V _1w ^* are output from the primary voltage command calculation circuit 8. That is, d-axis and q-axis correction voltage components ΔV _1d and ΔV _1q are output from the correction voltage component calculation circuit 7 via the input terminals 80 and 81, respectively. Where (32)
In the equation , since the d-axis component V _1d of the primary voltage is zero when there is no load, ΔV _1d is equal to the d-axis component command V _1d ^{* of the} primary voltage.
Become equal. On the other hand, the adder 84 adds the no-load voltage command V _1q0 ^* output from the no-load voltage calculation circuit 5 via the input terminal 82 to the q-axis correction voltage component ΔV _1q, and the equation (32) is obtained. operation on the right side of the equation for V _1q is performed for, it is outputted as the primary voltage of the q-axis component command V _1q ^*.

Thereafter, the adder 1 is connected via the input terminal 83.
6, when the correction primary frequency command ω ₁ ^** is input, the same operation as the correction current component calculation circuit 6 described above
Multiplying the sin [theta ₁ ^* and cos [theta] ₁ ^* digital amount of output from the M87 is input to the multiplication type D / A converter 88 to 91, after analog conversion and input to the subtractor 92 and the adder 93 (12) Is calculated, and the α-axis component command V ₁ α ^* and the β-axis component command V ₁ β ^{* of the} primary voltage are calculated ^.
Is required. Thereafter, the operation of the expression (8) is performed by the coefficient units 94 and 97 to 99, the subtractor 95 and the adder 96, and the primary voltage commands _V1u ^* , _V1v ^* and V are output from the output terminals 100 to 102, respectively. _1w ^* is output.

Thereafter, these primary voltage commands V _1u ^* , V
_{When 1v} ^* and V _1w ^* are input to the variable frequency power conversion circuit 3, the operation of the induction motor 1 is performed by the same operation as in the first embodiment.
Are controlled so as to follow these primary voltage commands, respectively.

In the above-described embodiment, the case has been described where the difference between the absolute value of the torque current limit value I _1qmax ^* and the absolute value of the torque component current I _1q or a value obtained by inverting the sign thereof is proportionally integrated in the torque limiting circuit. Alternatively, the configuration of the torque limiting circuit 15 may be changed as shown in FIG.

That is, in the torque limiting circuit 15a in the block diagram shown in FIG.
Are input only to the amplification type integrator 126 with reset. The output of the reset-type integrator 126 with reset is
It is output from the output terminal 130 as the primary frequency correction value Δω ₁ ^* . Therefore, the amplification type integrator 126 with reset
While the is reset, the primary frequency correction value Δω ₁ ^* is zero
Therefore, the torque limiting circuit 15 shown in FIG.
There is an advantage that the signal switch 129 is unnecessary.

In the above embodiment, the torque limiting circuit 1
5 shows a case where the difference between the absolute value of the torque current limit value I _{1q max} ^* and the absolute value of the torque component current I _1q or a value obtained by inverting the sign thereof is directly proportionally integrated or integrated. modified as shown in 13, is multiplied by the torque current limit value I _1Qmax ^* and torque current I difference in absolute value of _1q and torque current I _1q multiplier 133, the signal switching device 132 by its polarity The output may be switched to either 1 or -1.

That is, in the torque limiting circuit 15b in the block diagram shown in FIG. 13, the torque component current I _1q input from the input terminal 121 is _{calculated based on the} torque current limit value I _1qmax ^* input from the input terminal 120. The value whose absolute value is obtained by the absolute value circuit 131 is subtracted by the subtractor 122, and the output of the subtracter 122 and the torque current I _1q are multiplied by the multiplier 1
Multiplied by 33. The output of the multiplier 133 is connected to the signal switch 1
32, the signal switch 132 outputs 1 when the output of the multiplier 133 is positive or zero, and outputs −1 to the amplification-type integrator 126 with reset when the output of the multiplier 133 is negative. The output of the amplifying integrator 126 with reset is output from the output terminal 130 as a primary frequency correction value Δω ₁ ^* .
Note that, similarly to the above embodiment, the amplification type integrator 12 with reset
Reference numeral 6 denotes an output of the multiplier 128, that is, the product of the primary frequency correction value Δω ₁ ^* output from the amplification type integrator 126 with reset and the torque component current I _1q is positive or zero. Resets the held integral to zero. Accordingly
To increase or decrease the primary frequency correction value Δω ₁ ^* at a constant gradient.
Can be.

Embodiment 3 FIG . Next, an embodiment of the third invention will be described with reference to the drawings. FIG. 14 is a block diagram showing the overall configuration of the third invention, wherein 1 is an induction motor, 2 is a current detector, and 3 is a variable frequency power conversion circuit, for example, a transistor inverter circuit 21 and a PWM circuit in a conventional device. 25. 4 is an excitation current command setting device, 5 is a no-load voltage calculation circuit, 6 is an error current component calculation circuit, 7 is a correction voltage calculation circuit, 8 is a primary voltage command calculation circuit, 17 is a torque command setting device, and 18 is torque. A minute current command calculation circuit, 19 is a subtractor,
200 is a torque control circuit.

Incidentally, since the above-mentioned 1 to 8 have the same structure and operation as the circuit described in the above embodiment, the description is omitted here. However, in the block diagram showing the detailed configuration of the correction voltage calculation circuit 7 shown in FIG.
Although the corrected primary frequency command ω ₁ ^** has been input,
In this embodiment, a primary frequency command ω ₁ ^* is input.

FIG. 15 is a block diagram showing a detailed configuration of the above-described torque component current command calculation circuit 18. In the figure, the torque component current command calculation circuit 18 includes a divider 142.
, An input terminal 141 connected to the coefficient unit 143, and an output terminal 144.

FIG. 16 shows the torque control circuit 200 described above.
FIG. 3 is a block diagram showing a detailed configuration of FIG. 1. In the figure, a torque control circuit 200 includes an input terminal 150 connected to a coefficient unit 151 and an amplification type integrator 152, and an output terminal 154 connected to an adder 153. It is configured.

Next, the operation of the third embodiment will be described with reference to FIGS. As shown in FIG. 15, the torque command _Te ^* output from the torque command setter 17 via the output terminal 140 is input to the divider 142. The exciting current command I _1d ^* output from the exciting current command setting device 4 via the input terminal 141 is input to the coefficient device 143. Next, the torque command T _e ^* is divided by the output of the coefficient unit 143 by the divider 142.
The result is output from the output terminal 144 as a torque current command I _1q ^*.
, That is, the torque component current command calculation circuit 1
At 8, the equation (35) is executed.

Next, as shown in FIG. 14, the torque component current command I _1q ^* output from the torque component current command calculation circuit 18 in the subtracter 19 is the primary current output from the error current component calculation circuit 6. , That is, the torque component current I _1q is subtracted, and the result is output to the torque control circuit 200. The torque control circuit 200 inputs the difference between the torque component current command I _1q ^* and the torque component current I _1q from the input terminal 150 as shown in FIG. Then, the output of the coefficient unit 151 and the output of the amplification type integrator 152 are added by the adder 153, and the output is output from the output terminal 154 as the primary frequency command value ω ₁ ^* .

Although the third embodiment of the present invention has been described, the torque control circuit 200 directly proportionally integrates the difference between the torque component current command I _1q ^* and the torque component current I _1q. The configuration of the control circuit 200 is changed as shown in FIG. 17, and the difference between the torque component current command I _1q ^* and the torque component current I _1q is input to the signal switch 156, and the output of the signal switch 156 is changed according to the polarity. You may switch to either 1 or -1.

That is, in the torque control circuit 200a in the block diagram shown in FIG.
The difference between the torque component current command I _1q ^* and the torque component current I _1q input to the signal switch 156 is input to the signal switch 156.
6 amplifies 1 when the difference between the torque component current command I _1q ^* and the torque component current I _1q is positive or zero, and amplifies -1 when the difference between the torque component current command I _1q ^* and the torque component current I _1q is negative. Shape integrator 15
7 is output. After that, the output of the amplification type integrator 157 becomes 1
It is output from the output terminal 158 as the next frequency command value ω ₁ ^* .

In the above embodiment, the primary resistance R ₁
Is corrected in the correction voltage calculation circuit by using the d-axis and q-axis components I _1d and I _1q of the primary current, the correction voltage calculation circuit 7 and the primary voltage command calculation The configuration of the circuit 8 is changed as shown in FIG. 7 and FIG. 8, respectively, and the voltage drop is detected by the primary current I _1u detected by the current detector 2.
And I _1v .

That is, in the correction voltage calculation circuit 7a of the block diagram shown in FIG. 7, the error current component I _{err of the} equation (32) is obtained.
_{Are calculated} and output as correction voltage components ΔV _1d0 and ΔV _1q0 on the d-axis and the q-axis. That is, ΔV _1d0 and ΔV _1q0 are given by Expression (30).

Furthermore, these correction voltage components ΔV _1d0 , Δ
If via the input terminals 80a and 81a of the V _1Q0 entering the primary voltage calculation circuit 8a of the block diagram shown in FIG. 8, and ignoring the voltage drop caused by each primary resistance R ₁ from the coefficient multiplier 97 to 99 Primary voltage commands V _1u0 ^* , V _1v0 ^*, and V _1w0 ^* are output.

Next, when the U-phase primary current output from the current detector 2 via the input terminal 103 is input to the coefficient unit 107, the voltage drop V _Ru due to the U-phase primary resistance R ₁ is obtained. Therefore, when added to V _1u0 ^* by the adder 110, a U-phase primary voltage command V _1u ^* including a voltage drop by the primary resistor R ₁ is output from the output terminal 100.

Similarly, the V-phase primary current output from the current detector 2 via the input terminal 104 is
8, the adder 111 _obtains a V-phase primary voltage command V _1v ^* including a voltage drop due to the primary resistor R ₁ , and outputs it from the output terminal 101.

Next, regarding the W phase, first, the known (3)
Using the equation (1), the adder 105 and the sign inverter 106 determine the W-phase primary current I _1w from the primary currents I _1u and I _1v . In the same manner, W including the voltage drop due to the primary resistance R ₁ is calculated by the coefficient unit 109 and the adder 112.
Since V _{Wu of the} phase is obtained, V _1W0
^When added with ^* , a W-phase primary voltage command V _1W ^* including a voltage drop due to the primary resistor R ₁ is obtained from the output terminal 102 and output from the output terminal 102.

Further, as another embodiment, the voltage drop due to the primary resistance is converted into the α-axis and β-axis components I ₁ α and I _{1 of the} primary current.
The correction may be performed in the primary voltage command calculation circuit using β. Further, although the primary current I _1W is obtained by calculation from I _1u and I _1v , a value detected by a current detector can be used.

[0169]

The present invention is configured as described above.
Therefore, the following effects can be obtained.

A current detecting means for detecting a primary current of the induction motor; a no-load voltage calculating means for generating a no-load voltage command value from a primary frequency command value and an exciting current command value;
Secondary current, the exciting current command value, the primary frequency command value,
Of the primary magnetic flux generated inside the induction motor
The critical value is the excitation current command value and the primary self
Set value of primary magnetic flux given by product of inductance and
Error current component calculation means for generating an error current component that becomes zero when the values coincide with each other; primary resistance correction means for generating a correction amount of a primary resistance set value from the error current component; a correction voltage arithmetic means for generating a correction voltage from the correction amount and the said primary resistance set value and the error current component the primary current and the previous SL primary frequency command value of the value, the said no-load voltage command value A primary voltage command calculating means for generating a primary voltage command value of the induction motor from the correction voltage and the primary frequency command value, so that the primary resistance set value is true of the primary resistance of the induction motor. When the value deviates from the value, the primary resistance set value is corrected so as to match the true value of the primary resistance, and the primary magnetic flux is controlled to be constant according to the set value. There is an effect that stable control that does not occur can be performed.

Also, the primary resistance correcting means calculates the error current component.
Calculates (proportional + integral) to generate the correction amount of the primary resistance set value
Control the error current component to zero.
And the effect of bringing the primary resistance set value closer to the true value of the primary resistance
There is fruit.

[0172] The correction voltage arithmetic means primary by multiplying the primary resistance set value and the current component of the measured value of the primary current the sum was converted to d-q axes of the correction amount of the primary resistance set value Since the voltage drop due to the resistance is corrected, when the primary resistance set value deviates from the true value of the primary resistance of the induction motor, the error current component is corrected to be zero, and the primary magnetic flux is corrected. There is an effect that the control is made constant according to the set value.

[0173] Further, a voltage drop due to the correction voltage arithmetic means primary resistance set value and the correction amount and by multiplying <br/> measured value of the primary current to sum the primary resistance of the primary resistance set value When the primary resistance set value deviates from the true value of the primary resistance of the induction motor, the error current component is corrected to zero, and the detected primary current is directly used. This has the effect of controlling the primary magnetic flux to be constant according to the set value.

A current detecting means for detecting a primary current of the induction motor, and a no-load voltage calculating means for generating a no-load voltage command value from a primary frequency command value, a primary frequency correction value and an exciting current command value. And the primary current, the exciting current command value, the primary frequency command value, and the primary frequency correction value.
Actual value of primary magnetic flux generated inside the induction motor by force
Is the excitation current command value and the primary self-input of the induction motor.
Matches the set value of the primary magnetic flux given by the product of the conductance
And error current component calculation means for generating an error current component such that zero when the primary frequency correction primary resistance set value and the error current component the primary current and the previous SL primary frequency command value Correction voltage calculating means for generating a correction voltage from the value, a primary voltage command value of the induction motor from the primary frequency command value, the primary frequency correction value, the no-load voltage command value, and the correction voltage. A primary voltage command calculating means for generating the torque; and a torque limiting means for generating a primary frequency correction value from a predetermined torque current limit value and the primary current. And the primary frequency correction value increases or decreases the torque current and limits the torque current so that it does not exceed the set value, so that the generated torque of the induction motor can be limited so as not to exceed the set value, And overcurrent There is an effect of suppressing.

Further , the torque limiting means is provided with a predetermined torque current.
The difference between the current limit value and the absolute value of the torque current of the primary current is generated.
The difference signal generating means, and the signal from the difference signal generating means.
Change the polarity of the signal according to whether the torque current is positive or negative
First signal switching means for performing the
Has a reset function to process these signals (proportional + integral)
Proportional integration means, and a signal from the proportional integration means
Generates the product of the primary current and the current for the torque and the polarity of the signal
Multiplying means for resetting the proportional integration means according to
According to the polarity of the signal from the multiplying means, the proportional integral
Output from the stage as a primary frequency correction value.
Signal switching means, the absolute value of the torque current
Is less than a predetermined torque current limit value,
The positive value is set to zero, and the absolute value of the torque
Predetermined torque current limit value when the above flow limit value and the primary
The difference between the current torque and the absolute value of the current is processed (proportional + integral).
Is the primary frequency correction value.
When the absolute value of the torque current is equal to or greater than the specified torque current limit value
Only the generated torque can be limited by the primary frequency correction value
effective.

Also, the torque limiting means is provided with a predetermined torque current.
The difference between the current limit value and the absolute value of the torque current of the primary current is generated.
The difference signal generating means, and the signal from the difference signal generating means.
Change the polarity of the signal according to whether the torque current is positive or negative
First signal switching means for performing the
These signals are integrated and output as a primary frequency correction value
Integrating means having a reset function;
Generating a product of a signal and a torque current of the primary current,
Multiplying means for resetting this integrating means according to the polarity of the signal
And the absolute value of the torque current is equal to the predetermined torque.
When the current is below the current limit value, reset the integrating means.
The primary frequency correction value is set to zero, and the absolute value of the torque
When the torque current is equal to or greater than the specified torque current limit value, the specified torque current
Integrates the difference between the limit value and the absolute value of the torque current of the primary current
The processed value is used as the primary frequency correction value.
No signal switching means 2
Only when the pair value is equal to or greater than the specified torque current limit value,
There is an effect that the generated torque can be limited by the wave number correction value.

Further , the torque limiting means is provided with a predetermined torque current.
The difference between the current limit value and the absolute value of the torque current of the primary current is generated.
The difference signal generating means, and the signal from the difference signal generating means.
And a first product for generating a product of a signal and a torque current of the primary current.
And the polarity of the signal from the first multiplying means.
Signal switching means for outputting a positive or negative predetermined value according to the
The signal from this signal switching means is integrated and subjected to primary frequency compensation.
Integrating means having a reset function of outputting as a positive value,
The signal from the integrating means and the current corresponding to the torque of the primary current
And the integration means according to the polarity of the signal.
Reset multiplying means, so that the torque
Integral when the absolute value of
Reset the means to set the primary frequency correction value to zero,
When the absolute value of the divided current is equal to or greater than the specified torque current limit value
Is the primary frequency obtained by integrating the positive or negative predetermined value
The correction value is used, and a predetermined torque current limit value and 1
1 irrelevant to the value of the difference between the torque of the next current and the absolute value of the current
There is an effect that the generated torque can be limited by the next frequency correction value.
You.

A current detecting means for detecting a primary current of the induction motor, a no-load voltage calculating means for generating a no-load voltage command value from a primary frequency command value and an exciting current command value,
The primary current, the exciting current command value, and the primary frequency
Primary magnet generated inside the induction motor by inputting
The actual value of the bundle is the exciting current command value and one of the induction motor.
Of primary magnetic flux given by product of secondary self inductance
Correction from the error current component calculation means, the primary resistance set value and the error current component the primary current and the previous SL primary frequency command value for generating an error current component such that zero when matches the value Correction voltage calculation means for generating a voltage, primary voltage command calculation means for generating a primary voltage command value for the induction motor from the primary frequency command value, the no-load voltage command value, and the correction voltage; Torque control means for generating a primary frequency command value from the current command value and the primary current, so that the primary magnetic flux is controlled to be constant according to the set value,
The primary frequency command value controls the torque generated by the induction motor, and there is an effect that the torque generated by the induction motor can follow the command value.

Further, the torque control means includes a torque current finger.
The signal of the difference between the command value and the torque current of the primary current is (proportional + product
Minute) and outputs it as the primary frequency command value.
Generated from the difference between the torque current command value and the torque current of the primary current
The primary frequency command value is used to control the generated torque.
And the difference between the torque current command value and the torque current of the primary current.
Effect of high-precision torque control so that the value of
There is.

Then, the torque control means includes a torque current finger.
Depending on the polarity of the signal of the difference between the current value and the torque current of the primary current
Signal switching means for outputting a positive or negative predetermined value
Integrates the signal from the signal switching means and sets the primary frequency command value
And integration means for outputting as
The primary frequency command value generated by integrating the predetermined value of
Control the torque, and specify the generated torque on average.
The effect of simple torque control that matches the
You.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a control device for an induction motor according to Embodiment 1 of the present invention.

FIG. 2 is a no-load voltage calculation circuit according to Embodiment 1 of the present invention;
5 is a block diagram showing the.

FIG. 3 is a block diagram showing an error current component calculation circuit 6 according to the first embodiment of the present invention .

FIG. 4 is a primary resistance correction circuit 9 according to the first embodiment of the present invention;
FIG.

FIG. 5 is a diagram illustrating a correction voltage calculation circuit 7 according to the first embodiment of the present invention;
FIG.

FIG. 6 is a block diagram showing a primary voltage command operation circuit 8 according to the first embodiment of the present invention .

FIG. 7 is a correction voltage calculation circuit 7 according to the first embodiment of the present invention;
It is a block diagram which shows a.

FIG. 8 shows a primary resistance correction circuit 8 according to the first embodiment of the present invention .
It is a block diagram which shows a.

FIG. 9 is a block diagram showing a configuration of a control device for an induction motor according to Embodiment 2 of the present invention.

FIG. 10 is a torque limiting circuit 1 according to a second embodiment of the present invention .
5 is a block diagram showing the.

FIG. 11 is a diagram illustrating a correction voltage calculation circuit according to a second embodiment of the present invention;
7 is a block diagram showing the.

FIG. 12 is a torque limiting circuit 1 according to a second embodiment of the present invention .
It is a block diagram which shows 5a .

FIG. 13 is a torque limiting circuit 1 according to a second embodiment of the present invention .
It is a block diagram which shows 5b .

FIG. 14 is a block diagram showing a configuration of a control device for an induction motor according to Embodiment 3 of the present invention.

FIG. 15 is a block diagram showing a torque component current command calculation circuit 18 according to Embodiment 3 of the present invention .

FIG. 16 is a torque control circuit 2 according to a third embodiment of the present invention .
It is a block diagram showing 00 .

FIG. 17 is a torque control circuit 2 according to a third embodiment of the present invention .
It is a block diagram showing 00a .

FIG. 18 is a block diagram showing a configuration of a conventional control device for an induction motor.

FIG. 19 is a T-type equivalent circuit per phase of the induction motor of the related art and the present invention .

FIG. 20 is a pattern diagram of a function generator in a conventional induction motor control device.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 induction motor 2 current detector 3 variable frequency power conversion circuit 4 excitation current command setting device 5 no-load voltage calculation circuit 6 error current component calculation circuit 7 correction voltage calculation circuit 7a correction voltage calculation circuit 8 primary voltage command calculation circuit 8a 1 Primary voltage command arithmetic circuit 9 Primary resistance correction circuit 15 Torque limiting circuit 15a Torque limiting circuit 15b Torque limiting circuit 16 Adder 17 Torque command setting device 18 Torque component current command calculating circuit 19 Subtractor 20 Primary resistance setting device 22 Frequency command Generator 190 Torque current control value setting device 200 Torque control circuit 200a Torque control circuit

Claims (11)

(57) [Claims] 1. A control device for an induction motor which converts a voltage and a current of the induction motor into dq coordinate axes rotating at a primary frequency and controls the current, a current detection means for detecting a primary current of the induction motor, A no-load voltage calculation means for generating a no-load voltage command value from the primary frequency command value and the exciting current command value; and the primary current, the exciting current command value, and the primary frequency reference value.
Primary magnet generated inside the induction motor by inputting
The actual value of the bundle is the exciting current command value and one of the induction motor.
Of primary magnetic flux given by product of secondary self inductance
Error current component calculation means for generating an error current component that becomes zero when the value matches a constant value; primary resistance correction means for generating a correction amount of a primary resistance set value from the error current component; a correction voltage arithmetic means for generating a correction voltage from said primary resistance set value and the correction amount of the resistance set value with said error current component and the primary current and the previous SL primary frequency command value, the no-load voltage command value And the correction voltage and the primary frequency
And a primary voltage command calculating means for generating a primary voltage command value for the induction motor from the command value . 2. The control device for an induction motor according to claim 1, wherein the primary resistance correction means calculates the error current component (proportional + integral) to generate a correction amount of the primary resistance set value. 3. The correction voltage calculating means includes a primary resistance set value and 1
The measured value of the primary current is calculated as d-
control device for an induction motor according to claim 1, characterized in that by multiplying the current component which is converted to q-axis corrected voltage drop caused by the primary resistance. 4. The correction voltage calculating means includes a primary resistance set value and 1
Next resistance set value of the correction amount and the control device for an induction motor according to claim 1, wherein the correcting the voltage drop caused by the primary resistance measurements of the primary current ride Flip <br/> Te to the sum of . 5. A control device for an induction motor which converts a voltage and a current of the induction motor into dq coordinate axes rotating at a primary frequency and controls the current, a current detection means for detecting a primary current of the induction motor, A no-load voltage calculating means for generating a no-load voltage command value from the primary frequency command value, the primary frequency correction value, and the exciting current command value; and the primary current, the exciting current command value, and the primary frequency reference value.
Command and the primary frequency correction value, and
The actual value of the primary magnetic flux generated inside the machine is the excitation current command
The product of the value and the primary self inductance of the induction motor
It becomes zero when it matches the set value of the given primary magnetic flux
And error current component calculation means for generating an error current component such as, primary resistance set value and the error current component the primary current and the previous <br/> Symbol primary frequency command value and said primary frequency compensation value And a correction voltage calculating means for generating a correction voltage from the first frequency command value, the primary frequency correction value, the no-load voltage command value, and the correction voltage. A control device for an induction motor, comprising: a primary voltage command calculating unit; and a torque limiting unit that generates a primary frequency correction value from a predetermined torque current limit value and the primary current. 6. A torque limiter includes: a difference signal generator configured to generate a difference between a predetermined torque current limit value and an absolute value of a torque component current of a primary current; and a polarity of a signal from the difference signal generator. First signal switching means for changing the torque component current according to positive or negative; proportional integration means having a reset function for processing (proportional + integral) a signal from the first signal switching means; Multiplication means for generating a product of the signal from the proportional integration means and the current corresponding to the torque of the primary current and resetting the proportional integration means in accordance with the polarity of the signal; and in accordance with the polarity of the signal from the multiplication means 6. The control device for an induction motor according to claim 5, further comprising: second signal switching means for outputting a signal from said proportional integration means as a primary frequency correction value. 7. A torque limiter includes: a difference signal generator configured to generate a difference between a predetermined torque current limit value and an absolute value of a torque component current of a primary current; and a polarity of a signal from the difference signal generator. First signal switching means for changing the torque component current depending on whether the current is positive or negative, and integration means having a reset function for integrating a signal from the first signal switching means and outputting it as a primary frequency correction value And a multiplying means for generating a product of a signal from the integrating means and a current corresponding to the torque of the primary current and resetting the integrating means in accordance with the polarity of the signal. 6. The control device for an induction motor according to claim 5. 8. A torque limiter includes: a difference signal generator configured to generate a difference between a predetermined torque current limit value and an absolute value of a torque component current of a primary current; a signal from the difference signal generator and the first signal; First multiplying means for generating a product of the next current and the torque component current; signal switching means for outputting a positive or negative predetermined value according to the polarity of a signal from the first multiplying means; An integrating means having a reset function of integrating a signal from the means and outputting it as a primary frequency correction value, and generating a product of the signal from the integrating means and a torque component current of the primary current to generate a polarity of the signal 6. A control device for an induction motor according to claim 5, further comprising: a multiplying means for resetting the integrating means in response to the control signal. 9. A control device for an induction motor that converts a voltage and a current of the induction motor into dq coordinate axes rotating at a primary frequency and controls the current, a current detection unit that detects a primary current of the induction motor, A no-load voltage calculation means for generating a no-load voltage command value from the primary frequency command value and the exciting current command value; and the primary current, the exciting current command value, and the primary frequency reference value.
Primary magnet generated inside the induction motor by inputting
The actual value of the bundle is the exciting current command value and one of the induction motor.
Of primary magnetic flux given by product of secondary self inductance
And error current component calculation means for generating an error current component such that zero when matches the value, the primary resistance set value and the error current component the primary current and previous <br/> Symbol primary frequency command Correction voltage calculation means for generating a correction voltage from the value, a primary voltage command calculation for generating a primary voltage command value for the induction motor from the primary frequency command value, the no-load voltage command value, and the correction voltage. Means, and a torque control means for generating a primary frequency command value from a torque current command value and the primary current. 10. The torque control means outputs a signal representing a difference between a torque current command value and a torque component current of a primary current (proportional + integral).
The control device for an induction motor according to claim 9, wherein the control device outputs the primary frequency command value. 11. A torque control means comprising: a signal switching means for outputting a predetermined positive or negative value according to the polarity of a signal representing a difference between a torque current command value and a torque component current of a primary current; 10. An induction motor control device according to claim 9, further comprising integrating means for integrating said signal and outputting as a primary frequency command value.